1. Field of the Invention
In general, the present invention relates to a method and apparatus for forming an unstable product produced by an intimate mixing of ingredients, the resultant unstable product remaining stable following the mixing for a relatively short period of time under normal ambient conditions, and for packaging the unstable product within a suitable container for the dispensing thereof.
More particularly, the present invention relates to a method and apparatus for the forming and packaging of delayed foaming gels within suitable containers.
2. Description of the Prior Art
As used herein, the term "delayed foaming gel" denotes a viscous emulsion of at least an aqueous surfactant (for example, water and a soap or detergent) and a volatile foaming agent (e.g., a volatile hydrocarbon such as isopentane, isobutane, a mixture of such hydrocarbons, or the like, for example, fluorocarbons) wherein the volatile foaming agent is included in the internal phase of the emulsion. Various skin conditioners, lubricants, oils, perfumes, dyes, perservatives, etc. can also be included.
Such gels find use in the personal care field. One such known product is a delayed foaming shaving gel which is expelled from an aerosol container in the form of a gel, but which thereafter converts to a foam upon vaporization of the foaming agent. However, such delayed foaming gels are seen to have other applications, e.g., shampoos and other cleansing products, skin lotions, so-called "mousses", etc., and the present invention is not to be limited to delayed foaming shaving gels.
To prevent premature foaming, such delayed foaming gels are customarily packaged such that there is no appreciable air space for the gel to foam into prior to being dispensed from the container. That is, the gel should completely fill the container and there should be, to the gretest extent possible, no headspace or enclosed void spaces into which the gel can foam.
Quite often, so-called "barrier" aerosol containers are used to merchandise such gels, wherein the gel is densely packed into a collapsible bag suspended within an aerosol can. A propellant contained between the "barrier" and the outer wall of the can serves to dispense the gel by collapsing the bag when the valve is opened. However, other containers such as pump dispensers could be used for the merchanidising and dispensing of such gels, and the present invention is not to be limited to the use of so-called "barrier"aerosols.
If an aqueous surfactant along with any added emulsifiers, oils, perfumes, etc. (herein collectively referred to as "concentrate") is intimately mixed with an appropriate foaming agent such that the foaming agent enters and becomes emulsified in the internal phase, a delayed foaming gel will be produced. However, packaging of such a gel raises considerable problems. Due to its high viscosity, it is difficult to densely pack such a gel into a suitable container without producing void spaces which allow premature foaming.
One known approach to packaging similar gels is to "spin fill" the containers. The containers are rotated rapidly around their longitudinal axes as the product is introduced. The resultant centrifugal forces tend to fully fill the containers without leaving voids. Clearly, however, such a technique requires intricate and quite expensive packaging machinery.
Another process is shown in U.S. Pat. No. 4,405,489, wherein an aqueous soap ingredient and a post-foaming agent are mixed and the mixture is then placed in a pressurized and refrigerated holding tank for a time sufficient to form a gel prior to being introduced into suitable containers. This patent teaches the use of pressurization and refrigeration to maintain the already formed gel in a condition capable of continuously flowing through the system for introduction into the container.
Conventional aerosol foams do not present the particular handling and packaging considerations outlined above. Such conventional aerosol foams are usually packaged in conventional aerosol containers by first partially filling the container with a soap solution and thereafter charging the container by injecting a suitable propellant through the valve of the container.
U.S. Pat. No. 3,013,591 discloses a particularly notable method and apparatus for charging conventional aerosol containers already containing product with a propellant through the container valve. Gassing devices incorporating the teachings of this patent are manufactured and sold by The Kartdrig Pak Co. of Davenport, Iowa, for example their Model No. 939. The construction and operation of such devices are also shown in various Kartridg Pak publications, such as their "Manual for Undercap Gasser 939".
Inasmuch as the present inventors have utilized certain principles taught in this patent in the present invention, U.S. Pat. No. 3,013,591, which is discussed more fully below, is hereby expressly incorporated by reference.